Design and implementation of a virtual relay feeder protection

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UNIVERSIDAD DE LOS ANDES

Design and implementation of a virtual

relay feeder protection

Juan David P´erez Osorio

Supervisor:

Gustavo Andr´

es Ramos L´

opez

Examiner:

Mario Alberto Rios Mesias

Submitted in fulfilment of the requirements for the Degree of Bachelor in Electrical Engineering

Engineering Faculty

Department of Electrical and Electronic Engineering

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Author’s Declaration

1. I am aware that any fraud in this thesis is considered a serious offense in college. By

signing, deliver and present this proposal Thesis or Graduation Project, I express testi-mony that this proposal was developed in accordance with standards established by the University. Similarly, assure you that I did not participate in any kind of fraud and at

work concepts or ideas that are taken from other sources are properly expressed.

2. I am aware that the work that I perform include ideas and concepts of the author and the Advisor and may include course materials or previous work in the University and

therefore, give proper credit and I will use this material in accordance with human rights standards copyright. Likewise, I will not publications, reports, articles and presentations at conferences, seminars or conferences without review or authorization of the Counsel

who represent in this case the University.

Signature:

Nombre: Juan David P´erez Osorio C´odigo: 201017066

C.C.: 1022380780

Date: May - 2016

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UNIVERSIDAD DE LOS ANDES

Abstract

Engineering Faculty

Keywords: ANSI Functions, State machine, COMTRADE file, oscillography, Virtual relay, Co-simulation, LabVIEW, DSSim-PC.

In this grade’s project was develop a computational model of a ritual relay, with the purpose of saving expenses to make validations of protection coordination in power systems and

vali-date algorithms to make a good practice of protection coordination. The principal protection function added to this virtual relay design in Labview was the ANSI functions 27,59,50,51,79

and 86 that are described in the content of this document its model and function. Other important function that has this relay is the generation of COMTRADE files to record os-cilography of a event according to the standard IEEE C.373.111-1999. Finally it was made

a validation of this model comparing COMTRADE obtained through simulation in hardware in the loop with the files that the virtual relay generated.

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UNIVERSIDAD DE LOS ANDES

Abstract

Engineering Faculty

Palabras Clave: Funciones ANSI, Maquina de estados, Archivos COMTRADE, Oscilo-graf´ıa, Rel´e virtual, Co-simulaci´on, LabVIEW, DSSim-PC.

En este proyecto de grado se desarrollo un modelo computacional de un rel´e virtual, con

el fin de ahorrar costo para poder realizar validaciones de la correcta coordinaci´on de protec-ciones en sistemas de potencias y validar algoritmos para realizar una buena coordinaci´on de

protecciones. Las principales funciones que se le añadieron a este relé diseñado en Labview fue las funciones de preotección ANSI 27,59,50,51,79 y 86 que son descritas en el contenido

de este documento su función y modelado. Otra funcion que tiene el relé es el de generación de archivos COMTRADE para guardar la oscilograf´ıa de un evento según el estándar IEEE C37.111-1999. Finalmente se realizo la validación de este modelo comparando con archivos

COMTRADE obtenidos mediante simulaci´on por hardware in the loop con los archivos que generaba el rel´e virtual.

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Acknowledgements

First I want to thank Gustavo Ramos for his support and guide in the development of this

work. Second to recognize the support and help of David Celeita, who inspire and guide me when the work was not complete and had errors to fix them and continue until I reached the goals of this job .

Finally I want to thank my parents and aunt David P´erez, Elizabeth Osorio and Concepci´on

P´erez, who always believe in me and help me with their emotional and economical support through these years of studies.

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List of Figures

4.1 Example of TC curve to configure a 51 function [1] . . . 5

4.2 Reclosing Schema [1] . . . 6

7.1 State machine for overcurrent and voltage protection - logic . . . 14

7.2 State machine for auto-reclosing - logic . . . 15

7.4 Front panel of the virtual relay in LabVIEW . . . 18

8.1 Overcurrent event[2] . . . 23

8.2 Overvoltage event [2] . . . 23

8.3 Overcurrent COMTRADE switch SW 2 . . . 24

8.4 Overvoltage COMTRADE switch SW 3 [2] . . . 24

8.5 IEEE 13 node test feeder and a 3 phase fault at bus N 692 . . . 25

8.6 COMTRADE results for Three phase fault bus N 692 . . . 25

8.7 COMTRADE results for single phase fault bus N 692 . . . 26

8.8 Reclosing sequence operation . . . 26

8.9 Virtual relay COMTRADE record for F1 318000 . . . 27

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List of Tables

6.1 Work Schedule . . . 11

7.1 Constants for Time Current Curves according to [3] for ANSI equations . . . . 20

8.1 Relative error for Cases A and C . . . 29

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Chapter 1

Introduction

In the Colombian power systems occur a problem to configure a protection relay, because to configure a relay, engineers look the oscillography of the system and see an event that happened, then configure the relay to protect the system from this event. In other words this

configuration is made post mortem.

It would be desirable to prevent an event in the system before this occurs in the system, for

this reason is important to develop a model of the relay and try different failures and possible configuration to do a good coordination of protections. In this project we develop a virtual

relay with the functions 27, 50P/N, 51P/N, 59, 79 and 86 of protection according to the ANSI nomenclature.

Additionally in a project where it’s needed to evaluate what instruments of protection to buy, this model gives an important way of making this evaluation before and reducing costs of equipment. This is possible because the model could be implement to simulate a network and

see where and what is needed in order to protect a power system.

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Chapter 2

Objectives

2.1 General objectives

The principal objective of this thesis is to implement and prove the operation of a virtual relay for feeder protection. With the goal of giving a virtual relay more complete and easy to program new functions with educational and research purpose.

2.2 Specific objectives

The specific objectives of this work are presented in 3 different tasks:

• Implementation of the ANSI function 27, 50, 51, 59, 79 in the virtual relay.

• Generation of COMTRADE files in the model of the virtual relay.

• Prove the correct operation of the virtual relay develop in this thesis.

2.3 Scope and final product

The commitment of this thesis was to give a model of a virtual relay with some protection functions and make a validation of the model. The model must have at least the functions of overcurrent, overvoltage, undervoltage and a reclosing sequence and the generation of

COM-TRADE files of an event in a system.

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Chapter 3

Problem description and work

justification

The main problem that encourage this thesis is to reduce expenses of equipment in test of a system or algorithms to find faults with the help of relays. Because a single relay can

be very expensive and a power system could have multiples relays to coordinate its protection.

So in order to make simulation with adaptive controls or to verify the coordination of the protection in the system, there is the need to have a computational model of the relay. With the help of DS-Sim PC that is a free software, the prototype could be done.

There are software that make coordination of protection like DigSilent or Etap , but these

softwares collects money through a license and are not practical to develop new protection function. The model developed can be easily modified to add a new protection function, giving the advantage to configure and add new tools in this area with great importance.

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Chapter 4

Theoretical and historical

framework

4.1 Theoretical framework

First for this work it is important to define what should do every protection function

imple-ment in the model of the virtual relay, for this reason we are going to explain the protection function that the project models. And second we have to explain what a COMTRADE format is, because thanks to this format we will be able of making a comparison between a real relay

and the model created.

4.1.1 Function 27: Undervoltage relay

This function is a very simple one, the relay should send a signal to open the breaker if the voltage is under a parameter define. But in order to prevent a premature action, the function

should wait some programmed time, because this undervoltage could be occasioned for a transient maneuver for example the energization of a motor could reduce the voltage.

4.1.2 Function 59: Overvoltage relay

The function 59 is similar to the 27 function but with a little differences, instead of protecting the system of an undervoltage this one should act when the voltage is bigger than a limit

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List of Tables 5

voltage. Like the function 27, the function 59 should wait time to act, because the overvoltage could be the result of a transient manoeuvre like the disconnection of a big load in the system.

4.1.3 Function 50: Instantaneous overcurrent relay

This function works with the current and the principle is that if the current measure is bigger than one programmed then the relay should send the signal to open the breaker. But like the

function explain previously it should wait some time because this event could be a transient event like the energization of transformers or motors.

4.1.4 Function 51: Inverse time overcurrent relay

The function 51 is the first complex protection function explain in this document, this function works also with the current like the 50, but with the difference that it does not work with

constant current. This function works with curves of current vs time like the one in the figure 4.1. When the time and current of an event is higher than the curve that is configure then

the relay should give a signal to open the breaker.

This function has standards curves according to IEC and ANSI, and each curve has some

characteristics depending on how fast this curve decays. The name of this curve are time inverse curves.

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List of Tables 6

4.1.5 Function 79: AC Reclosing relay

This function tries to reconnect the breaker and waits to see if the fault is gone or if the fault stay in the system. The scheme of reclosing can be seen in the figure 4.2 where one can see

that when the relay begin the sequence first waits a dead time and then the recloser sends a pulse to the breaker to close the breaker and finally it waits to see if the fault vanished or stay. The recloser can do this sequence n times, where n is an integer number define by the

user.

Figure 4.2: Reclosing Schema [1]

4.1.6 Function 86: Lockout relay

This function is implemented to prevent a reclose of the line if it is not programmed, the function should not work if the signal of any lockout is on. And only when the engineer is

sure that everything is working correctly in the system, he should reset the lockout and give the instruction to close the breaker.

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List of Tables 7

4.1.7 COMTRADE (Common format for transient data exchange) for power systems

A COMTRADE file is a file where is recorder some event of a power systems. This file is com-posed for two essential extension .dat and .cfg, where the .dat extension has the information

of the signal that are being measured at a point in the system and are configure to be saved.

The .cfg extension has information about what represent the signals recorded in the .dat extension and information about the CT and PT recording the signal,also information of the time of the event and the standard version of the file.

There are two additional extensions that can have a COMTRADE File .inf and .hdr where the

file.inf has additional information of the equipment and the .hdr has additional information added supplementary information about the location of the device that record this file.[4]

4.2 Historical framework

The research of testing and analysis modeling for relaying automation has identified significant challenges, one of them complies testing concerns of substation based protection with realism, flexibility, scalability and open simulation tools [5].

These efforts have been constant objectives in the evolution of protective relaying modeling; for example, DYNA-TEST [6] was originally developed for protection relay applications and

it was proposed almost 25 years ago, at the same time when the COMTRADE Standard C37.111 [7] was urgently needed.

Protective relaying literature and history show that both, research and industry standardiza-tion guarantee the progress of this field and it is consistent with upcoming needs. Although,

one of the main requirements for relay testing with hardware/software integration is low cost usage of commercial computer hardware and system software support [8].

Previous works with relay’s modeling have presented excellent features in real applications,

but always taking into account the limitations of each model [9]; certainly, virtual environ-ments, real-time models and test beds where improved after a decade of the COMTRADE

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List of Tables 8

The interaction between protective devices, relay models and power systems simulations [2, 12–14], have shown the effectiveness of these research in various applications such as protection coordination, adaptive protection, reconfiguration and so forth.

Most of these studies include at least one or two protective devices, but the progress of this research field requires a higher number of relaying equipment in order to obtain better

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Chapter 5

Definition and work specification

5.1 Definition

The problem definition is to construct a model for a virtual relay in a distribution system implemented in DSSim-PC. Therefore it can be only used the model for thee types of systems.

On the other hand the libraries developed here can be easily transform to use to model a transmission power system.

5.2 Specification

A list of restriction to consider the use of project in further works like simulations or imple-mentations of new power systems are:

• The power system where the virtual relay can operate is a distribution system

imple-mented in DSSim-PC.

• The curves implemented in the ANSI function 51 are the ones in the Anderson book [3]

and in the manual of the relay Micom P145 of Schneider [16].

• The standard use to record a COMTRADE file used by the vitual relays is the 1999

standard[17].

• The validation of this model is only made in a simulation.

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List of Tables 10

• In the interface of the virtual relay, the protection engineer will see only the curve from

a single relay.

• This relay a general one and it will not try to behave exactly like a specific relay, else it

will protect with the state machine implemented.

With these restrictions, the project can work as desire, because the restrictions do not attend with the principal objectives proposed in the section 2. And if is wanted to give more freedom

of restrictions, it can be done except for the one changing the state machines proposed to model a general relay. If this wants to be changed, the whole structure of the relay should be transformed.

Moreover if there is the need to add any other curve for the 51 function, it can be added

by just putting the equation of the curve inside a switch case in Labview. Or if there is the need to see all the curves in one the programmer can make a cluster of the TC curves and

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Chapter 6

Work methodology

6.1 Workplan

The table 6.1 shows the list of activities and approximation of the time spent in each activity,

it is important to stand out that the time used in some activities was simultaneous, because some times when a bug in the model was found it requires to change the whole structure of the virtual relay.

Table 6.1: Work Schedule

Activity Time used

State of the art 3 weeks

Model of ANSI function 27 2 weeks

Develop a logic for the virtual relay 2 weeks

Communication with DSSim PC 2 weeks

COMTRADE files generation 1 week

Virtual Relay Validation 2 weeks

To solve questions that appeared in the course of the project there were 2 meetings weekly one with Gustavo Ramos on Tuesday and the other with David Celeita PhD student on

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List of Tables 12

Wednesday, thanks to these two meetings when a problem or worry about the theory and how to program something in Labview, these meeting helped to solve or give and alternative in the seek of finishing the project.

6.2 Seek of information’s sources

The seek of information has 2 types of information, by personal reference as David Celeita or Gustavo Ramos. The second one was using the online resource of the university library such

as IEEE explore, science direct, books.

The main sources used was the Anderson book of protection coordination, online books and

manuals of Schneider Electric and meetings with David Celeita to develop some state machines to use as models of the functions implemented.

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Chapter 7

Work done

7.1 Relay design and modeling

According to the standardization [18] and manufacturers, a set of ANSI functions are selected to develop a virtual model of each function. For feeder’s protection the model should include

at least overcurrent functions for primary protection (ANSI 50P/51P and ANSI 50N/51N). Undervoltage and overvoltage functions are also integrated in the virtual relay (ANSI 27/59)

and the reclosing sequence function (ANSI 79). In order to validate the operation in different fault scenarios, COMTRADE files are recorded following [7], [4] and based on the state ma-chine programmed to the MiCOM P145 [16] with the concepts reported in [1]. The following

subsections describe the state machine of each function and the logic operation:

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List of Tables 14

7.1.1 Overcurrent protection and Voltage protection

Figure 7.1: State machine for overcurrent and voltage protection - logic

Protection against abnormal scenarios of voltage or current levels must be addressed when protecting a feeder. Three states are defined for undervoltage, overvoltage and overcurrent

protection as shown in Fig.7.1.

At the first state, the machine is waiting for an abnormal situation; certainly, in case of an

excess of current, the state will move to Stand by state no matters if there is a programmed ANSI function 50 or 51. This will also occur in case of abnormal voltage levels.

The stand by state defines if the abnormal situation continues for a period of time; nevertheless

this time value is previously programmed by the user. There are two conditions to change:

• If the condition vanished in the programmed time.

• If the condition stand still along the programmed time.

In the first case the machine moves back to the first state. Otherwise, the machine will move to a Lockout state if an abnormal condition continued, which means that the programmed

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List of Tables 15

time was accomplished with the abnormal scenario. To return to the normal state the user should reset the state machine.

ANSI functions 50P/51P, 50N/51N, 27 and 59 will work with the state machine previously presented in Fig.7.1.

7.1.2 Reclosing sequence

The state machine to include the auto-reclosing feature (ANSI function 79) in the virtual

relay design is proposed taking into account three different fault conditions: (1) transient, (2) semi-permanent and (3) permanent. According to literature and experience, most of overhead

line faults are caused by lightening and temporary contact with external objects such as trees or wind movement. Since these kind of faults do not last for a long time, the transient nature of this phenomena will possibly allow successful re-energization of the system after the trip

of the protection equipment.

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List of Tables 16

The first state defines a normal condition, therefore the machine will wait until it receives the reclose signal to begin a re-energization process. If the breaker is not healthy but a reclose signal is activated, the machine is taken to a lockout state.

If a reclose signal is activated and the breaker condition is healthy, the machine will move to the stand by state; Likewise the state machine explained in the previous subsection, stand

by states are designed to wait pre-programmed periods of time, so in this case the machine will wait until the dead time passed and then it will decide to which state the machine will

continue.

Note that the stand by state is the only one which can move to all the states:

• If the dead time has passed and the breaker is closed it will go back to the normal state.

• If the dead time has passed, and the breaker is opened but it is not healthy, the machine

will move to a lockout state.

• If the breaker is opened, and the machine has tried all the tripping sequence to reclose

after the dead time passed, the next state will be the lockout condition.

• If the dead time has passed, and the breaker is open and healthy, the machine will allow

a reclose condition.

In the reclose state, the machine will give the pulse signal to reclose the breaker and it will wait until the reclaim time has passed. Then, a sequence trial is accomplished and the machine

goes back to the stand by state. Finally, the lockout state is included in case where the breaker is not healthy or the reclosing sequence has totally passed but the fault remains in

the network. This state machine is shown in Fig.7.2.

7.1.3 COMTRADE generator and event monitoring

Since the standard was developed by the Power System Relaying Committee, the idea was to take advantage of digital computer based devices capable of record data from transient events

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List of Tables 17

Figure 7.3: State machine for COMTRADE recorder

The standard allows the data exchange for analysis and validation of records [19]. With

the protective relaying evolution, technology has a wide range of purposes that still needs this standard in order to validate real-time simulations and hardware-in-the-loop testing.

Alternative solution of advanced automation, smart fault recorders, power quality tools and transient phenomena studies might be focused on COMTRADE files.

The state machine to perform a consistent COMTRADE recorder is proposed in order to be activated by a previous user configuration that allows an ANSI function trip to save the transient data.

This application includes important aspects of the standard about header, configuration files (.CGF) and sampling rates. The state machine starts in a pre-save state where the machine is

saving data in case some event occurs, therefore a pre-fault transient data is always recorded. When an event is triggered (this change of state is activated by the trip of a selected ANSI

function), the machine records data after the relay sends the trip signal.

The third and last state defines the machine when there is enough data to save a COMTRADE

file. In this state the machine saves the COMTRADE file and passes to the pre-save state as shown in Fig.7.3. It is important to note that the triggering of this feature and the recorded time are all configured by the user.

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List of Tables 18

7.2 Computational work

Figure 7.4: Front panel of the virtual relay in LabVIEW

A first version of the virtual relay was build to operate with DSSim-PC [20], a recent

distri-bution simulator software and the non deterministic version of the DSSim-RT simulator; This simulator is based in the powerful EPRI’s OpenDSS [21] and it can be used as a graphical

interface for it.

As shown in Fig.7.5, the online simulation of a distribution system is running on DSSim-PC, while a TCP/IP connection makes possible data exchange between the grid simulation and

the operation of the virtual relay. LabVIEW libraries of DSSim-PC are used to synchronize measurement acquisition and time steps (1 ms).

In a single computer the user can monitor the distribution system with a meters file previously saved in DSSim-PC, so the user could understand this window as a SCADA of the system. In a second window, the virtual relay monitor and control panel is operating so each function for

three phase or single phase protection is configured. In case of any event, the user is allowed to save COMTRADE files for records and post-fault analysis. The function logic designed in

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List of Tables 19 ONLINE SIMULATION Voltage meters Current meters Power meters Switch’s status Load profile monitor Fault’s programing

FEEDER MONITORING

Digital inputs and outputs V/i measurements Fault records IEEE C37.111 (COMTRADE) Lockout monitor Reclosing sequence Manual trip – close

RELAY CONTROL AND MONITORING

Feeder Simulation

Virtual Relay

ANSI Functions • 50/51 •67 •27/59 •79 • Harmonics Data exchange TCP/IP

· Undervoltage 27 P

· Overvoltage 59 P

· Inst. Overcurrent 50 P/N

· Overcurent 51 P/N

· Reclosing 79

· 50BF Breaker failure

User Front panel

Figure 7.5: Virtual relay design - software integration

7.2.1 TCCs - Overcurrent protection settings

Time current curves (TCCs) have a model equation shown as follows:

T

K

Mα₋₁ +L

+C (7.1)

Where K, α and L are constants corresponding to every standard curve. C is a pure delay applied to the TC curve, T is Time multiplier setting for IEC curves or Time Dial for IEEE

curves and M is the proportion of the measured current over the pick up current. The constants used to model the ANSI function 51 are shown in Table.7.1. The user can select

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List of Tables 20

Table 7.1: Constants for Time Current Curves according to [3] for ANSI equations

Characteristic Curves K L alpha

Definite time 0.2 0.18 1

Moderately inverse time 0.55 0.18 1

Short Time 0.2 0.015 1

Modified inverse time 1.35 0.055 1

Modified very inverse time 1.35 0.015 1

Inverse time 5.4 0.18 2

Very inverse time 5.4 0.11 2

Extremely inverse time 5.4 0.03 2

7.2.2 Current and Voltage protection logic

The current and voltage protection logic of the virtual relay works with the activation 2

voltage protection functions undervoltage (27) and overvoltage (59) and 2 current protection functions instantaneous (50) and inverse time (51). The user can configure each one of this protection function and decide which one wants to use to protect the feeder with a boolean

panel.

There is also the possibility of having different protection configuration in every single phase

or having the same configuration in the 3 phases for the implemented ANSI function. Finally the virtual relay has a reclosing sequence function (79).

7.2.3 Reclosing sequence configuration

To configure this function in the virtual relay there are 4 settings to define. First, the user

should give the reclaim time and dead time for each reclosing trial, second the user should configure how many reclosing trials are required. Then, to finish this setting the user must

press the activation of this function in the front panel, and finally, the user select which protection function wants to reclose, normally overcurrent functions. The operation of the

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List of Tables 21

7.2.4 COMTRADE settings and records

In order to save an event, the virtual relay use COMTRADE files using the COMTRADE library of LabVIEW. It is important to highlight that this library saves a COMTRADE

file according to [17] from 1999, assuming that the PT and CT rates are 1:1, because the communication with DSSim-PC shares data about voltage and current measurements with the real values in the switch.

To adjust the COMTRADE settings, the user must define the path file where the COM-TRADE file will save and name of the file. Then the program needs two time windows to

know how much data to save before and after the trip, therefore these times are taken in milliseconds. Finally in order to avoid rewriting a COMTRADE file, the program will save

the name put in the path file in addition with the event time stamp when it was created.

7.2.5 User’s interface - Virtual relay monitor and control panel

Fig.7.4 shows the front panel of the proposed virtual relay, which has 4 sub-panels. The biggest one (left side of the figure) there is the configuration panel where parameters for

ANSI functions 27, 50P, 51P, 59 and 79 can be configured. At the end of this panel there is a button to graph a TCC curve in the TCC Viewer. The TCC Viewer panel has a button

to configure if the user wants to see the current axe in multiples of the pick up current. The next panel is the simulation and COMTRADE configuration where the relay controls the co-simulation link with DSSim-PC (the user selects the node and the switch to be controlled)

and the COMTRADE configuration. Finally the last panel (right side in the bottom) voltage and current measurement are presented in RMS values, and there is also a calculation of the

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Chapter 8

Work validation

8.1 Test methodology

To prove the correct performance of the virtual relay there were controlled different breakers with the virtual relay in 3 systems and from this systems there is 2 with COMTRADE files

to compare the results with the ones give it by the virtual relay. The one that does not have COMTRADE files is used to prove the behaivor of the protection 51P for single and tree

phase fault and a reclose sequence. For both systems with COMTRADE files are simulated faults as the ones in the COMTRADE files from hardware in the loop simulation with real relays.

8.2 Work Validation

In the next subsections shows the reader can see the results of the 3 system implemented in DSSim-PC used to validate the virtual relay develop in the last section.

8.2.1 Case A

Based on a simple case that was tested using two relays in a RT-HIL tested [2], an overvoltage

and an overcurrent protection are implemented using now the virtual relay. There is a basic feeder and two branches each one with a certain load.

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List of Tables 23

Load LD 1 is highly sensible to overvoltage phenomena. A three phase fault is programmed at the bus N 6 near to load LD 2, which is 4 times higher than LD 1.

The first event is shown in Fig.7.1 , the overcurrent protection is tripped in one of the vir-tual relays (TCC=IEC extremely inverse C5). Up next, the action of that relay causes an overvoltage in the bus N 2 due the disconnection of load LD 1. This event is shown in Fig.7.3

Figure 8.1: Overcurrent event[2]

Figure 8.2: Overvoltage event [2]

The corresponding COMTRADE generated by the virtual relays in both events are shown in Fig. 7.3 for overcurrent and Fig.7.4 .The relative error in the overcurrent value and the

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List of Tables 24

overvoltage is calculated using the equation 8.1, which is lower than 3.6%. Results are shown in Table.8.1.

Figure 8.3: Overcurrent COMTRADE switch SW 2

Figure 8.4: Overvoltage COMTRADE switch SW 3 [2]

8.2.2 Case B

In this example, the IEEE 13 node test feeder shown in Fig.8.5 which is one of the default systems that DSSim-PC brings to the user is studied. This highly loaded 4.16 kV feeder is

quite small and it has a recloser between nodes N 671 and N 692. Although the example is previously validated with load flow and short circuit according to the original test feeder.

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List of Tables 25

Figure 8.5: IEEE 13 node test feeder and a 3 phase fault at bus N 692

The idea is to reproduce a 3 phase fault and a single phase fault to ground in the bus N 692, therefore the user can see the operation of the virtual relay with this phenomena and obtain the

COMTRADE file associated to these events. To do so, the original TCC curve is programmed in the virtual relay.

COMTRADE Files for both events are shown:

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List of Tables 26

Figure 8.7: COMTRADE results for single phase fault bus N 692

And finally, for this case the reclosing sequence is activated and succesfully performed:

Figure 8.8: Reclosing sequence operation

Note that ANSI function was programmed to make a reclosing sequence with 2 trials. The

first trip is detected and the breaker opens almost in 1 cycle. Approximately 60 ms after this trip, a reclosing trial is activated but the fault remains active. Finally after 140 ms The

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List of Tables 27

8.2.3 Case C

Since this particular and useful case was tested in real-time [15] for understanding and training with protection coordination in industrial systems, the implementation of the virtual relay

allows to expand the benefits of the real-time test bed for protective relaying control. The advantage of this application contributes to a better interaction with the standard 242-2001 because the user can now implement each relay with a virtual environment, which means an

important highlight to be include in academia (protection courses), professional training with real distribution systems models and future standardization.

Using the model of IEEE 242-2001 in DSSim-PC, the results for faults F1 138000, F1 4160 and F2 4160 are tested using virtual relays. Relative error between the real-time results and

COMTRADE acquired by the virtual relay in the three different failure scenarios show that the operation is consistent not only with the standard but also seems alike with the real-time COMTRADE results. The COMTRADE results for faults F1 138000, F1 4160 and F2 4160

with the virtual relay, that seems to be highly consistent with the obtained results in [15] are presented in figures 8.9,8.10 and 8.11 .

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List of Tables 28

Figure 8.10: Virtual relay COMTRADE record for F1 4160

Figure 8.11: Virtual relay COMTRADE record for F2 4160

8.2.4 Results

The equation used to find the relative error of the 2 Cases with COMTRADE files is the

equation shown in (8.1), where it can been seen that this equation is scale to percentage scale.

εr =

Xi−Xv

Xv

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List of Tables 29

The table 8.1 shows the comparison between the COMTRADE file in [15] for the system of the standard IEEE 242-2001 and the system found in [2]. The data use to compare was the peak current and voltage in the fault moment.

Table 8.1: Relative error for Cases A and C

COMTRADE Relative error Vp (%) Relative error Ip(%)

Case A

Overvoltage 3.57

-Overcurrent 3.28 1.42

Case C

F1 138000 5.29 0.82

F1 4160 0.3 0.45

F2 4160 0.3 1.43

It can be seen that the maximum value of error is 5.2 % and the other ones are relative small.

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Chapter 9

Conclusions

This thesis presented the first version of a virtual feeder protection relay. The operation of the proposed relay shows consistency with results previously tested on real-time studies. The Std C37.111 for COMTRADE and event recording was successfully integrated within the virtual

relay so protective studies can be done using this first model and running distribution systems in DSSim-PC.

The validation of the virtual relay performance is assessed with voltage and current

phenom-ena with 3 different case of study. The relative error between real-time hardware-in-the-loop results and the virtual relay, is lower than 5.3%.

The virtual relay is versatile, scalable and flexible to design new protection algorithms. Fur-ther works are propose like implementing the communication protocol IEC 61850, adding new

function like the 21 ANSI function (distance relay) or using the libraries developed to control a transmission system with co-simulation in other software as DigSilent.

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Design and implementation of a virtual relay feeder protection

UNIVERSIDAD DE LOS ANDES